Porta Viridaria

The Porta Viridaria, also known as the Porta San Petri, Porta di Belvedere, Porta Palatina, Porta Aurea, and the Porta San Peregrini, is a gate in the outer wall of the Vatican City.

History
Porta Viridaria is one of the oldest gates in the walls surrounding the Vatican City. It opens into Leonine City, or the Borgo, an independent municipality that sits at the entrance to the Vatican. Both were enclosed by the Leonine Walls in 852 to defend against invaders. Once built, the Porta Viridaria became the primary entrance to the Vatican from the north, welcoming the influx of pilgrims. The gate was rendered unnecessary in 1563, when the third set of Leonine Walls were constructed, enclosing the existing set.